Research

Joanne Chory, a Professor in the Plant Biology Laboratory, is interested in identifying the mechanisms by which plants respond to changes in their light environment. She and her colleagues use genetic, genomic and biochemical approaches in the reference plant, Arabidopsis, to identify components of the phototransduction pathways, with emphasis placed on the events mediated through a family of red/far-red-light-absorbing receptors. Her laboratory has identified mutants in these photoreceptors and in nuclear-localized signal transduction components. Work in Dr. Chory's lab has also led to the discovery of a steroid hormone, brassinolide, that controls plant development in response to light, and has identified the plant steroid receptor and signaling pathway.

"Our lab is interested in identifying the mechanisms that
plants use to respond to changes in their environment,
particularly light. Our hope is that by discovering the
molecular triggers that determine whether a plant matures
into a spindly or robust specimen, we can contribute to
efforts to increase crop yield and alleviate hunger."

Stuck where the seed germinates, plants
have to make the best of their real estate.
They rely on an arsenal of light-sensitive
photoreceptors to decide when to germinate
and flower to ensure the next generation of
seeds. The Chory laboratory studies the signaling
pathways plants use to detect changes
in the sunlight that hits their leaves, not only
when seasons change, but also when they
grow in shady, crowded conditions. She and
her group have assigned specific functions
to a number of photoreceptors that regulate
plant growth, identified components of the
light signaling pathways, and shown that
photoreceptors link hormone biosynthesis
and signaling pathways within the plant to
the local light environment.

Chory's laboratory has made significant
contributions to the studies of three major
plant hormones. Her team identified the steroid
receptor and signaling pathway utilized
by all flowering plants. They determined
the structure of the receptor for a class of
small hormones called cytokinins, which are
utilized as herbicides. And they solved the
long-running mystery of how plants produce
auxins, which play essential roles in plant
growth and development. Recently, Chory's
laboratory showed that the major plant auxin
is synthesized by a simple pathway from the
amino acid, tryptophan.

Chory is also investigating how genetic
variation in light-sensitive pathways in thale
cress plants ensures that plants in northern
latitudes are more sensitive to light than
those in the sun-drenched Mediterranean.
Using a reference strain of the plant, her
team is assessing the contribution of almost
every gene to light sensing and signaling in
a variety of light environments. Knowing the
full spectrum of genes that can be altered
in the laboratory to affect an adaptive trait—
and how this compares with the genes that
affect plants' appearance in the wild—will
advance understanding of how genes evolve
together to make an efficient, coordinated
network. This work is important not only to
evolutionary biologists and plant breeders,
but also to human biology, where similar
experiments cannot be carried out. Chory's
research may eventually enable researchers
to develop plants that are particularly welladapted
to challenging environments, boosting
the yields of agricultural crops.